Open-fire tunnel kiln



Feb. .3, 1925.

P. DH. DRESSLER OPEN FIRE TUNNEL KILN Original Filed Hatch 24, 1921 3 Sheets-Sheet iNVNTDR ATTORNEY H. DRESSLER OPEN FIRE TUNNEL KILN Rmb A Feb, 3, 1925,

. Original Filed ATTORNEY Feb. 3, 1925 P. DYH. DRESSLER OPEN FIRE TUNNEL KILN Original Filed March 24, 1921 3 Sheets-Sheet 3 INVENTOR (l #Me 19u/4M Patented Feb. 3, 1925.A

unirse STATES msm e'rsr orme..

PHILI? DHUC DBESSLER, F CLEVELAND, OHIO. ASSIGNOR TO AMERICAN DBESSLER TUNNEL KILNS, `INC., 0F CLEVELAND. OHIO. A CORPORATIGN OF NEW YORK.

OPEN-HIRE TUNNEL KILN.

Application filed March 24, 1921,`Seral No. 455,062. Renewed July 11, 1924.

To n?! mlm/fi il may concern le it known that l. Pmmr nHUC Duess- Licn. u subject of the King of Great Britain,

kilns are or may be emplojv'ed where the' conditions are such as to permit the kiln to he heated by the How of burning gases and hot products of combustion through y.the kiln chamber. The general object of the present invention is to provide an openfired tunnel kiln construction and .method .of operating the saine which Will permit of the'desired graduation in the kiln chamber.temperature longitudinally of the kilh; While substantially minimizing temperature variations tween points located zit different vertical levels in any transverse vertical plane through the high temperature section of the kiln. Y i

ln u continuoustunnel kiln suitable for burnin; brick. with any-reasonable etlinicucr and complicity. thcl kiln chamber must he nl" considerable length. For example, :loll feet may be assumed to he a typical length ol kiln though such kilns are somethin-s nmdeshorter and are frequently made longer than this. lVith the assumed length ot kiln chumher a portion of say-GO feet or so in length at the entrance end of the kiln fof-uis :i prcheuting zone, and a portion at the other end of tliekiln ot 100 lect in length or so forms the cooling zone, uhiknn intermediateportion of 140 feet iuso forms' the heating?r up. furnace, or high lo h-nipei'ntnrc burning zone. The bricks to be iuuut or other goods' heated are moved linx-'nigh such a kiln on cars which are in- Serti fill the kiln chamber which is thus nornnillj-y lillcd hv a train ot such cars, one cer beine renzored at. 'the exit end of the cooling zone of thc kiln euch time a car is inserted et the entrance end of the kiln. The

d in the entrance end of the kilnone .nt u time. and are then slowly moved through length of time required for the passage ot a Car through the kiln will depend on the character of the Ware being treated and 'the conditions of operation, but. in u kiln ot' the character referred to'by way of example ahore. it would be in accordance with usual practice to make each car six feet long and to insert a car every hour or so so that each cai' would require Something like hours .for its transit through the kiln. In akiln of this character the desired Inode of operation is one which 'rvill cause the bricks or the like passing through the kiln to gradually heat up from .the temperature at which they enter the kiln to the maximum temperature to which they are subjected, and to then cool down more Aor less uniformly, to a temperature at which they may be safely discharged from the kiln into the atmosphere.

Now it is obviously desirable. to insure a uniform product, that the various bricks or other goods on each kiln car, Whether located at the bottom or the top or at the sides or in the center ofthe pile of goodsv stacked on the cur,v be subjected not only to the same maximum firing tempera-ture,`

but to substantially the/same temperatures for substantially the same periods of time throughout the heating operaion.

ln a typical open tiredvkln as heretofore constructed, burning 'gases or vhot products of, combustionl or a mixture thereof are introduced 4into the kiln chamber along a comparatively short portion of the length of the high temperature' or irinfr zone of the kiln adjacent the junction ot that zone with the cooling'zone, and are'then drawn longitudinally of the kiln chamber toward the entrance end of theA letter, beingr ordinarily withdrawn from the kiln chamber proper,- at the junction of the burning and preheut ing zone., and then passed lengthwise of the preheatingzone of'the kiln through inuhes at the sides of the kiln chamber or throujrh heating tlues formed in the wells of the kiln. The vpurpose. of preventing heatingr fases from coming into contact `with the bricks or other were inthe prohosting zone of the` kiln vis to avoid discoloration and other injurious eilects produced by such con tact et low temperatures especially in the presence of moisture driven out of the were.

When the heating gases are thus intro so f luc.

duced into'the tiring zone of the kiln, along a relatively restricted portion of the length of the latter, and their flow through a substantial ortion of the burning 'Lone is longitudina, the temperature in the portion of the burning zone where the How is mainly longitudinal tends to be much higher at the top of the kiln than at the bottom of the kiln owing to the natural tendency of the hotter gases to pass to the top of the kiln chamber. Many arrangements have been proposed and tried to cause the heating gases to flow back and forth through the path 'traversed by the goods and in particular to compel them to flow through the lower portions of this path, but none of these arrangements have been effective to prevent the top of the burning zone at its cooler end from being much hotter than the bottom in kilns in which there is any substantial longitudinal flow of the heatinggases through the kiln chamber. In consequence it has been found necessary in tunnel kilns of this type t so concentrate the heat in the lower portion of the high temperature end of the burning zone that the lower layers of bricks'or the like on the cars receive heat much more rapidly in passing through this zone of the kiln than do the upper layers of brick. The result of this is that the bricks or other ware at the bottom of a car are at a lower temperature than the ware. at the top of the car duringr a considerable portion of their travel through the burning zone and aro then heated up at a rapid rate. as the car carrying the ware moves through the nal portion of the buming zone. With this mode of operation it is dillicult to insure that the ware at the top and bottom of a car arc subjected to the same maximum temperature, and impossible to cause the ware at the top and bottom of the ear to heat up at the same rates as is desirable to insure a uniform product.

In proceeding in accordance with the present invention I introduce the heating gases into the burningr zone of the kiln, not along a more or less restricted portion of the zone adjacent its high temperature end but along all or practically all of the length of the zone, and regulate the heating gases both as to temperature and volume so that they flow mainly in a vertical direction upward through the ware to the top of the kiln and in doing so heat the ware at the different levels to practically the same temperatures. Since with this mode of procedure the major portion of the heating is done by the gases in their upward flow through the brick it is unnecessary to make provisions for preventing the free longitudinal flow of partially` spent heating gases through the clearance Space between the roof ofthe kiln chamber and the tops of the stacks of ware on the cars. la some cases pro-virions may be made for withdrawing more or le-s of the heating gases from the top of the kiln chamber proper at intervals alongr the length of the burning zone. but ordinarily these gases need not he withdrawn from the kiln chamber until they are caused to pass out of the kiln chamber proper into the inutiles Yor heating tiues running alongside the preheating zone of the kiln.

By proceeding in accordance with the present invention the goods are subjected to a heat treatment analogous to that occurring in the well known up draft intermittent kiln wherein the temperature in the kiln is progressively increased throughout the period. usually 0f several days. required for a single burning operation. In the ordinary operation of such a kiln. asis wellknown. the burning operation starts, with the kiln and its contents cold. by igniting a little kindling wood in the kiln furnace chambers. and thenv'ood and finally coal or coke is added in small and carefully regulated amounts until a relatively high temperature is reached. after which the fuel is supplietkfreely until the maximum desired temperature is reached. lVith the. present invention the draft. is mainly upward throughout the tiring zone as in the interniittentl up draft kiln, and the temperature increases progressively along the length of the firing Zone.

As compared with previous open fired kilns, the present invention is distinguished by the fact that the total quantity of heat which is supplied to the kiln is distributed along a greater portion of the length of the kiln. This reduces the danger of local overheating of the kiln Structure..

The various features of novelty which characterize my invention are, pointed out with particnlarity in the claims annexed to and forming a part of this specification. For a better understanding of the invention. however, and its advantages, reference should be had to the aecompanving drawings and descriptive matter in which I havel illustrated and described a preferred embodiment of the invention.

0f the drawings: y

Fig. l is a. diagrammatic plan with parts broken away and in section;

Fig. Q iS a partial sectional plan on u larger scale than Fig. l;

Fig. 3 is an elevation in section on the line 3-3 of Fig. 2;

Figs. 4, 5, 6 and 7 are transversev sections taken on the lines Jr-'4. 5-5, 6-G, and 7 7, respectively, of Fig. l;

Fig. 8 is a diagram illustrating temperature conditions prevailing in the kiln.

Fig. 9 is a diagranunatie elevation illustrating the circulation in the kiln:

Fig. 10 is a diagrammatic elevationilluslli-i llt f lier of nozzles E.

l n tiring zone und a cooling zone c.

trati the circulation Vin a prior type of open reh intermittent kiln;

Fig. 11 is ii. diagram illustrating the teni rature conditions in the kiln shown in gli 10; and

. ig. 12 is 'a diagraninnitic elevation illus treating another prior type of open tired kiln.

The kiln construction shown in Figst 1 to 7 inclusive comprises an elongated kiln clnunhcr A divided into zi prelienting zone u, The bricks R or other goods to he heated are moved througliithey kiln on trucks running on track rails The truc-ks C nre l'ornied in the usual ninnncr with nictnllic l'i-iinie` and wheels nnd :i refractory hotly portion.

'The refractory body portion is formed iii its upper porti( n with transversely extending channels to which :ire open :it their outer ends to mceire the heating gases und are open all the way along or ait interviils along their top edgeis to permit the heating gases to pass upwzird into the Spaces between the bricks or nthergoods mounted on 'the trucks. The hi icks'or other goods are loosely smoked or arranged in the usual manner to permit the heating games to flow in more oi' less tortuous paths npwnrd through them. The heating gases are. admitted to the kiln chamber through orifices or nozzles IC which discharge the gases in horizontal jets nt the level of the open enter ends of the truck channels C and the parts should he so proportioned and the pressures so regulated that the jet velocities will he such :is to cause ull or practically zill of the heating gases delivered hy the nozzles li to enter the channels C and to piiss the proper portion ot the heating grises to the central portion of the triekr and the goods mountcd thcroon. ln the illustration shown the nozzles ll nre distrilnitcd nlong the entire length of burningl Zone The rihs or partitions lictwcen the channels C nre iidvzintagwusly tapered at their ends4 ns shown at C2. The heat-ing gases muy in some mises consist wholly or largely of combustible, mixtures of nir und gus which ignite und liurn lifter admission' to the, truck channels C. or they liniy consist of hot hut more or less cour pletely burned products4 of combustion. In the pnrticnlnr construction .shown the henting ,mises discharged through the nozzle nicnilicrs ll nrc nininl)Y hot products of coni hustion formed in the cluiniliers D which nre distributed zilongvt-he opposite sides ot' thi` kiln :ind serve lioth :is furnace chiunhei's in which fuel is hurnt. :ind as distributinf.' lines for ceri-ying the products of conihust ion fron'i each fuel hed to :iV lnrgel nuni- In the particular con struction shown each chamber D is provided :it one end with a grate l supporting :t fuel hed on to which coul or iiilogous solid Vfuel is passed from time to tiine. Vali'cd @tenui connections G from the steam supply pipe, G run to each grate D, and the stoom. thus supplied serres; :in is iniinil in turn this type to reduce clinkeriiig tronhlcsl i to induce thc proper intimv ot pi'innu-ji :in Secondary nir for the coniliustioi'i ol the coniliustililc gus-es rising' from the fuel lied iiic snpplicditc cach cluinilicr l) through u corresponding inlet li' regiiiiited by :i dumper l: from the ciiri'cspondinc secondaii'y nii' supply niziin l( of which. iii ine construction shown. tlicrc arc two. onc :it wich idc ot' the kiln. llairli conilnntion cli-.initier l i provided with si l'ncl inlet door l1' und nii :ish pit door l.

.\s `linnn thc inw/.lcs ll :ire in the forni of conn-:il paris4 rcnioi'iiiili sented in the kiln wall und they muy he nnide ol the .suine refractory nnitei'inl :is is cniiiinnniv-y used in thc gus hui'nciA inizi/lcs olk .'crticzil liuc coke ovenis. (lpposilc cnch nir/.Llc li :in opciiing, norniully clonal in' :i rel'riictoiw pini; l`.

is iidi'ninzingeously i'oinicd iii thc inici .i ntl of the corresponding cli-.initier l). 'liu-sc opcnin, |.-v permit inspection clcuning und icpincement of the linz/,ales lf. The. uninlivr ot coniluistion cluinilicrs l) employed l their dimensions nin) vitry quite n idcli` de pending on coiidit ioney of use. .shon n thcic ure seven clniniiiei's l) :it cncli .side olA the kiln. The three chunihcrs iit the high tcniperiiture end of the tiring zone :irc ndi-:iningeously. though not ncccss-irilyL nnidishortci than the other ciuiiiiieisund in one contemplated design of u kiln confftiucted in 'ticci'irdiizn with the present inn-nticu. the shorter clizinihci's l) :ire ein-li idiom li fc-ct in length. :ind the longer cliiiinliczc cuci :iliont :2.3 ticet ir length. lt is to ne invii-i2 stood that dimensions nrc given hy 'mii nlA illuistrntion und not, of liinitnlioii` The secondary eti .supplied to iliichriiii hers l) muy uilVnntzigeonsli' lie prcli-nntcii. und this is accomplished with the consti-ucY tion shown hy taking this nir through out` lets A from :i series ol hot, :iir pocket,` which :ire open iit their lower ends' und 'esta tend along the top of cooling zone ot' ihr kiln. adjacent pockets lieiiig sepninted hy tinnsvorne rilis or partitions l 'l`lie nii passing out otl the kilns through the outlet A10 enters ai conduit o." conduits l rainning' ulong the roof ofthe cooling zone ot' the kill: to nu exhaustl fun .l having liriinclicd outlets I leading to thc adjacent ends ol' thii'oi rcsponding hoty air duets K.

Conduite. are proiidcd nt the sides4 ot" the prcheziting' zone ot' thc kiln through which the heating gnscs nrc drziwn troni thi` uil-v jiicent cnd of thc tiring :rione el the, kiln und :ire passed to :i fsnilnhlc discharge stuck Q. A54 shown ilicsc coinliiits ccnipriru; portions` :idiineiit the junction of ,he preheiitiin :ind tiring' Zone which iii/c formed ot" ietncini tile sections l; haring oinn ended circuiti iii.

ini

loo

llt)

lill! tion channels L', such as are employed in the combustion chambers of the Well-known Dressler kiln, whereby a directed convection current circulation ci the kiln atmosphere. is niaintained.

In tho construction shown each of the two ilues formed one at each side of the kiln7 by the tile sections L, is connected at .its end adjacent the entrance end of the kiln to a. series ot conduits M which may be cast ironpipc. The pipes M at each side ol the kiln are connected at the entrance end ol the kiln to a corresponding junction box M opening through its bottom wall to a discharge passage t) connected to au out let liuc .ils shown the outlet flue 0 leads to the inlet o an exhaust fan l, the outlet ot which opens to the discharge stack Q.

lith the construction. illustrated, fuel and steam, and primaryv and secondary air are supplied to eachv combustion chamber as required to give the desired volume and.

temperature. of heating g: In gmcral ibo kiln temperature should vary longitudi nelly of the kiln as indicated by line TA in Fig. lVith such a kiln temperature the temperaturL of the goods vwill be that genn orally indicated bythe line T in Fig. 8. 1With tho described construction and modo of operation, it is comparatively easy, by properly proportioniig the orifices inV the nozzlos E, and by regulating the supply of fuel. air and steam to the chambers D to obtain a. kiln chamber temperature closely approximating the ideal temperature indicated by the line TA in Fig. lWith a kiln constructed and operating in accordance with the present invention the flow of thc heat ing gases throughout the entire length of the tiring zone of the kiln will he generally upward as indicated by the arrows in Fig. 9 and by suitably regulating the amount and temperature. of the heating gases approximate uniformity in temperatuiel at diiler eut levels in any plane, passing transversely to the lcnath ot thc kiln through its firing zone may be obtained.

lu this respect my present invention dill'crs broadly from open lire continuous tunnel kilns as ordinarily heretofore constructed and operated in which burning gases or hol products of combustion are introduced into the kiln chamber through a comparatively short portion or portions of the length oi' the tiring Zone ol` the kiln. To better dilllercrdiatc the present invention from prior constructions, I have shown in Fig. l() a diagrammatic representation of the geit eral path of flow of the heating gases in an open fire tunnel kiln wherein the burning gases or hot products of combustion are introduced into the kiln chamber through an orifice e which is relatively short and is located at the hot end ot the firing zone.

lVith such an arrangement the major portion of the heating gases will flow through the portion of the kiln indicated in Fig. 10 by the shaded area S, and the temperatlu'es at points along the length of the kiln lying Within this shaded area will be appreciably above the temperatures of corresponding points along the length of the kiln outside the shaded areas. In consequence of such temperature conditions when astack of bricks is moved througl'i the. kiln, the bricks at the top of the stack will heat up much more quickly than will the bricks at the bottom oi" the stack, and will startto cool sooner than will the bricks at the bottom of the stack. '.lhe bricks at the bottom of the stack will be subjected to a marked and unduly rapid increase in temperature when the. slack approaches the inlet orifice e.y In Fig. 1l, T indicates in a general way the\ temperature. variations of a brick at the top of the brick stack as it travels through the kiln, while T2 represents the temperature variations of a brick at the bottom of the stack. IVhcn, as has sometimes been done, a sin le furnace with a single inlet c is replacec by an arrangement in which there is a plurality of furnace inlets co as illustrated in Fig. 12, the temperature conditions indicated by Fig. l1 are varied in degree only; and not in kind, even though the oriices ea extend as they sometimes do along one-third or so of the length of the firing zone of the kiln.

The method of kiln'heating and the up'l paratus which I have devised for carryingout this method make possible any desired graduation in the 'temperature gradient along the length of the tiring zone of the kiln. `With my invention it is easily possi? ble to make the kiln atmosphere in any portion of the heating zone either oxidizing or reducing or neutral as conditions in ay requiro. Since with my invention the available heat in the heating gases iu mainly abstracted from the gases during their vertical uptlow through the kiln chamber there need he no substantial over heating ot' the top of the kiln with a corresponding tenth encyto over heat the goods adjacent the'top of the kiln and an undue los` of heat by radiation from the top of the kiln. The use of my invention perm'ts of a relatively simple and durable kiln structure.

VVhilo in accordance with the revisions of the statutes, I have illustrated and described the best form of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that ,certain features of my invention may sometimes bc used to advantage without the' corrisponding use ot other features.

Having ho\v,described xny invention, what l claim as new and desire to sure by Letters `Patent, is:

l. The method of maintaining a graduated temperature. along the length of an elongated heating zone of a tunnel kiln while minimizing temperature variations in any transverse plane through said zone which insists in introducing heating gases into the. kiln at the bottom ot the pathway through the kiln for the goods along the len th of said zone in such volume and at sae temperatures and under such conditions of pressure and velocity that the heating gases thus introduced will-[low mainly upward through said pathway from the points of gas introduction to the top of the pathway, and will impart the. major portion of their available heat to the goods in their upward movement through the goods path way.

2. In an open tire tunnel kiln comprising a preheating zone, an elongated heating zone, and a cooling zone, an heating flues along the preheating zone into which heat ing gases are drawn from the heating zone section of the kiln, the improvement which consists in provisions for passing heating gases into the lower portion of the kiln at istributed points along practically' the entire length of the heating zone.

Signed at Cleveland, in the county Cu a f 1o a and State of Ohio, this 16th day o Iarc A. D. 1921.

PHILir DHUo DRESSLER. 

